Railway signaling system



M y 7, 1946. A. L. JEROME I RAILWAY SIGNALING SYSTEM Filed April 25, 1944 4 Sheets-Sheet 1 W177)? Bamazelg J46 ('ami all d a \o dood M2 a v IN VEN TOR AmlzapLJe ome.

H15 ATgfpRNEY May 7, 1946. A. L. JEROME 2,400,005

- RAILWAY SIGNALING SYSTEM Filed April 25, 1944 4 Sheets-Sheet 2 ZWZZ ' HIS ATTORNEY y 1946- A. L. JEROME Q 2,400,005

RAILWAY SIGNALING SYSTEM Filed April 25, 1944 4 Sheets-Sheet 5 g ljihufLJerame.

HIS ATTORNEY izyza Patented May 7, 1946 RAILWAY SIGNALING SYSTEM Arthur L. Jerome, Edgewood, Pa., assignor to The Union Switch & Signal Pa,,-a corporation of Pe Company, Swissvale. nnsylvania Application April 25, 1944; Serial No. 532,603

My invention relates to ,a railway .signaling system for use on stretches of single track through which traificmay move in either direction but only in one direction atone time.

nn object of the invention isto provide an improved system which is arrangedso that a change in the established direction of traflic in the protected track stretch is effected by operationof a device located at the point at which it is desired to enter the stretch. y g fprther object of the invention is to provide an irnproved system of the ,typedescribed which is arranged so that the established direction of traffic cannot be changed while the stretch is occupied. l w ,1

Another object I of the invention is to provide animproved system of the type described which is arrangedso that an attempted change in the established direction of :traflic is ineffective if the stretch is occupied.

A further object Of'the invention is, to provide an improved system of the type described which is arrangedso that the established direction of traflic is altered only when a special type of energy is transmitted over the rails. of the track stretch to thereby prevent interference with the established direction of trafiic by trafiic or other, conditions. a g l V, W

Another object of the invention is to provide a system of the type described which is arranged so that, when the direction of trafllc is to be changed, traffic reversing energy is suppliedto thestretch at the end thereof at which it is desired t enter the stretch and is cascaded through all oi the sections to theother end of the stretch and ernust bereceived at the-other end of the stretchbefore a change is made in the established direction of traffic.

' A further objectofthe invention is to provide a system of the type described which is arranged so that, when the direction of, traflic is to be changed, the supply of traffic reversing energyto the track stretch is maintained until the traflic reversing function is completed. v

Another object of the invention is to provide a system of the type described which incorporates means to provide an indication of occupancy of the protected track stretch. l z

. A further object of the invention is to provide a system of the type described which operates without line wires, and in which all functions are per-- formed by energy transmitted over the rails of the track stretch,

Another-object of the invention isito provide;

a system of the type described which incorporates 13 Claims. (Cl. 246-33) means for normally. interrupting the supply. of energy to the lamps of the wayside signals for the established direction of traific, but effective on movement of a train through the stretch to supply energy to the lamps of the signals for the portion of the stretch in advance of the train.

A further object of the invention isto provide an improved signaling system of the type shown ,in, Letters Patent of thejUnited States No.

2,316,961, issued merer. 1 l

Other objects of the invention and features of novelty will be apparent from, the following description taken in connection with the accompanying drawings. I shall describe one form of railway signaling system embodying my invention andshall then April 1943, to R. R. 11Kempoint out the novel features thereof in claims.

In-the drawings:

Figures 1A, 1B, 1C and 1D, when placedtogether in the order named, form a diagram showing a stretch of railway track equipped with one form of signalling system provided by my invention, and

Figure 2 discloses a modification of the pick-up circuit for arelay of Figure 1A. Similar reference characters parts in both views. r

In practicing my invention, I provide each refer to similar track section in the track stretch with two sets of coded track circuit apparatus and. govern them by directional stick relays so that one set of track circuit apparatus is operated by master code and the other set; is operated by feed-back energy according as the stretch is conditioned for one direction of trafiic or the other. When the stretch is conditioned for either direction of trafiic, energy of trafiic governing code frequency is suppliedto the stretch at the exit end of the stretch and is repeated through the various sections to control trafilc in the stretch, while feed-back energy is supp ied over the section rails in the opposite direction and controls lighting of the wayside signals and also controls means at the exit end of the stretch to indicate whether ornot the stretch is occupied. The supply of feed-back energy to eachsection is dependent upon the supply of feed-back energy over the rails of the adjacent section-in the rear so that p when a train enters the stretch the supply of feed-back energy over all of the sections in advance of the train iscut off. 7

. When the established direction of traffic is to be changed, the supply of trafiic governing coded energy to the exit end of the stretch is cut off and coded energy of a distinctive trafiic reversing frequency is substituted therefor. This energy operates the track circuit apparatus for the various sections to release the directional stick relays and cause energy of this frequency to be repeated to the next section until it is received at the far end of the stretch where it energizes a directional rela and causes traflic governing energy to be supplied to the stretch at that point. This traffic governing energy feeds back through the traffic reversing energy and picks up directional stick relays to out 01f the supply of trafiic reversing energy to the section and cause trafiic governing energy to be supplied to the next section. When'traffic governing energy is received at the original exit end 'of the stretch, the supply of trafiic reversing energy is discontinued, while the supply of feed-back energy over the section rails is initiated and is repeated to the new exit end of the stretch.

The supply of traflic reversing energy to the stretch is controlled by the supply of feed-back energy over the rails of the stretch so that energy of this type can only be supplied to the stretch when the stretch is vacant.

Referring to the drawings there is shown therein a stretch of single track railway having track rails I and 2 over which traflic may move in either direction. Adjacent the left-hand or west end of the single track stretch is a passing siding or branch track WPS, and adjacent the righthand or east end of the single track stretch is a passing siding or branch track EPS.

Although this system is illustrated in connection with a single track stretch joining two passing sidings or branch tracks, the system is not limited to use in situations of this kind and may be employed wherever traffic may. move in either direction between two points, but only in one direction at one time.

The trackrails I and 2 are divided b insulated joints 3 into track sections for signaling purposes. As shown, there is a detector section WT which includes the switch connecting the passing. siding WPS with the main track, and a detector section ET which includes the switch connecting the passing siding EPS with the main track. The single track stretch between sections WT and ET is divided into track sections IT, 2T and 3'1, but it is contemplated that the single track stretch may include a larger or a smaller number of track sections.

The detector track sections WT and ET may be provided with track circuits of any appropriate type and, as shown, each of these sections is provided with a track circuit employing steady energy and including a track relay designated TR with an appropriate prefix.

Each of the track sections IT, 2'1 and ST is provided with coded trackcircuit apparatus arranged so that master code energy is at "times supplied to the section rails at one end of the section and feed-back energy is supplied to the other end of the section, while'at other times master code energy is supplied to-the other end of the section and feed-back energy is supplied to the one end of the section.

The track circuit apparatus for each section includes a code following relay at each end of the section, and each of these relays serves at times as the track relay and at other times as the feed-back detector relay.

Each code following relay'has associated therewith a battery TB which serves at times as a source of master code current and at other times as a source of feed-back current, while connection of each relay and each battery across the section rails is governed by a relay CTM which serves at times as a coding relay to cause master code impulses to be supplied to the section rails, and which serves at other times as an impulse relay to cause impulses of feed-back energy to be supplied to the section rails.

The code following relays are of the polar biased neutral type, while the energ supplied from the batteries to the section rails is supplied through the windings of the relays as shown in Letters Patent of the United States No. 2,286,002 to Frank H, Nicholson to prevent energization of the relay in the event of overlapping contacts onthe associated coding or impulse relay, or by inductive energy from the track circuit.

Movement'of traffic from left to right or eastbound is governed by signals ES, while movement of trainc from right to left or westbound is governed bysignals W S. As shown, these signals are of :the color light type, and each has a green or clear lamp G, a yellow or caution lamp Y, and a red or stop lamp R. While the signals are shown as being of the color light type, the system is not limited to the use of wayside signals of this type and any appropriate type of wayside signal may be employed.

Similarly, this signaling system is not limited to use in track stretches in which movement of trafiic is'governed by wayside signals and is adapted for use in track stretches in which movement of trafiic is controlled by cab signals, either alone or in conjunction with wayside signals.

A directional control relay MB is provided at each end of the track stretch and each of these relays controls the supply of traffic reversing energy to the track rails at that end of the track stretch. Each relay MR is provided with a pickup circuit controlled by a normally open push button PB, and with a stick circuit controlled by its own front contact and by a back contact of the clear signal control relay at that location.

While the pick-up circuits of the directional control relays are shown as being established by push buttons, the system is not limited to this arrangement, and these circuits may be controlled by remote control apparatus which may be of the type shown in Letters Patent of the United States No. 2,229,249 issued January 21, 1941, to Lloyd V. Lewis.

If this system is controlled by remote control apparatus, such as a C. T. C. system, a contact of a relay of the C. T. C. system is connected in multiple with each push button so that the C. T. C. system may be operated to establish a pick-up circuit for each directional control relay. If the system is controlled by a C. T. C. system, the push buttons provide means for locally controlling the direction of trafiic in the event the C. T. C. system is not functioning.

Each location is provided with a source of direct current, such as a storage battery not shown. the terminals of which are designated B and C in the drawings.

The equipment is shown in the condition which it assume when the stretch is vacant and is prepared for westbound trafiic.

At this time, relay WDR at the west end of the stretch is energized by current supplied over it's stick circuit which includes its oWn front contact I0 and back contact II of relay EFR. As relay WDR is picked up, relay IECTM is com nected over front contact I2 of relay WDR, front contact H of relay WTTR, and trafiic controlled tact I6 of relay WTI'R and front contact I! of relay :WDR to the recllamp R of signal IES and it is lighted to prevent entrance of an eastbound train into the stretch While it is conditioned for westbound traffic.

During the picked-up periods of relay IECTM energy is supplied from battery IWTBIovercontact 20 an'd'through the winding of relay .IETR' to the rails of section IT, while during the re-.

leased periods of relay. IECTM the track winding of relay IETR is connected across the'section rails. In addition,.when relay IECTM is released, its contact 2I permits energy to be sup plied over front contact 22 of relay IETR and.

front contact 23 of relay WDR to the holding winding of relay IETR.

The energy of 120 code frequencysupplied to the rails of section IT as a result of coding operation of relay IECTM feeds over backcontact 25 of relay IWCTM to the track winding of relay IWTR and operates the relay so that the two portions of the primary winding of the decoding transformer IWDT are alternately energized and energy is induced in the transformer secondary windings. transformer secondary windings is rectified by a contact of the relay IWTR and is supplied to the relay IWH and it contacts are picked up.

At this-time, the relay IWSR is energized by current supplied over it stick circuit Which includes its own front contact 26 and back contact 21 of the associated relay I WJ, and its contacts are picked up so that energy is supplied from the decoding transformer IWDT to relay 2D over the circuit which is traced from a terminal of a secondary winding of transformer IWDT over front contact 29 of relay IWSR and back contact 3!] of relay IESR to one terminal of the resonant rectifier unit I20DU, and from the other terminal of thi unit over back contact 3| of relay 2ESR and front contact 32 of relay ZWSR to the other terminal of the transformer secondary winding. As the relay IWTR is operated by energy of 120 code frequency, energy is supplied through the resonant rectifier unit IZIJDU to relay 2D and its contacts are picked up to permit energy to be supplied to the green lamp G of signal IWS when a westbound train enters the stretch.

As relay IWSR is picked up, and as relay ZEH is picked up, as explained below, energy i supplied from a secondary winding of transformer IWDT over front contact 33 of relay IWH, back contact 34 of relay IWJ, front contact 35 of relay 2EH, and front contact 36 of relay IWSR to relay IWCTM. The relay IWCTM and the corresponding relays at other points in the system are of a type the contacts of which pick up only when energy of a particular polarity is supplied thereto, while the apparatus is arranged so that energy of the polarity effective to pick up the contacts of relay IWCTM is supplied to the relay on release of the relay IWTR. Accordingly, each time the contacts of relay IW'IR release the contacts of relay IWCTM pick up momentarily so that energy is supplied from battery IETB over front contact 25 of relay IWCTM through Energy from one ofthe the track winding of relay IWTR to the rails of section IT. i

The energy supplied from battery IE'IB to the rails of section IT feeds over back contact 21: of relay IECTM to relay IETR and its contacts pick up so that contact 22 establishes the circuit of therelay holding winding to keep the relay picked up until relay IECTM picks up, whereupon relay IETR releases. As a result of code following operation of relay IETR energy is supplied through the transformer I EDT to the relay IEH and its contacts are picked up, while energy is not supplied to relay IED as it circuit is interrupted by contact 68 of relay WDR.

At this time, energy of code frequency is supplied to relay 2ECTM over the circuit which includes front contact 38 of relay IWH, back contact 39 of relay IWJ,front contact 40 of relay IWSR, and back contact 4| of relay ZESR, so relay 2ECTM operates to supply master code energy of 120 codefrequency to the rails of section 2T, and the equipment at the junction between sections 2T and 3T operates in the manner explained in detail in connection with the equipment at the junction between sections IT and 2T to cause master code of 120 code frequency to be supplied to the rails of section 3T and to cause feed-back energy to be supplied to the rails of section 2T,

The energy of 120 code frequency supplied to the rails of section 3T operates the track relay 3WTR so that energy is supplied through transformer 3WDT to relays 3WH and 3WD and their contacts are picked up so that relay 3WHP is picked up and energy is supplied to the green lamp G of signal 3WS over the circuit which includes front contact 42 of relay ETTR, back contact 43 of relay EDR, front contact 44 of relay 3WHP, and front contact 45 of relay 3WD. Accordingly,tthe green or clear lamp G of signal 3WS is lighted to indicate to Westbound trains that they may enter the stretch and that there are two unoccupied sections in advance of the stretch.

At this time, energy is supplied from a secondary winding of transformer 3WDT to relay 3 WCTM over front contact 46 of relay ETTR, back contact 52 of relay WFR, back contact I03 of relay 3WJ, front contact 41 of relay 3WHP, and back contact. 48 of relay EDR so the relay BWCTM operates to supply feed-back energy to the rails of section 3T and relay 3ETR operates and maintains relay 3EH picked up. When relay 3ETR picks up, its contact 50 establishes a circuit for the relay holding winding to keep the relay contacts picked up until relay 3ECTM picks up. The circuit of the holding winding of relay' 3ETR includes front contact 5| of relay ZWSR so the circuit is established only when the stretch is conditioned for westbound traific which is the only time the relay 3ETR is operated by feedback current and is the only time this circuit is required. A similar circuit is provided for relay 2ETR. and is controlled by a contact of relay IWSR.

As relay 3EH is picked up its contact 53 establishes the circuit for supplying energy from a secondary winding of transformer ZWDT to relay 2WCTM and it operates to supply feed-back energy to the railsof section 2T so that relay 2EH is picked up to establish the circuit for supplying energy from transformer IWD'I to relay IWCTM and thus cause feed-back energy to be supplied to the rails of section IT with the result that It will be seen that when the stretch is conditioned for westbound traffic and is unoccupied, master code is supplied at the west end of the stretch and is also supplied to the west end of each track section to thereby cause the signal at the east end of the stretch to provide a permissive indication, while feed-back energy is supplied to the east end of the stretch and is cascaded through the stretch to maintain relay IEHP at the west end of the stretch picked up. The relay lEI-IP may be employed in any appropriate manner at this time to indicate that the single track stretch is unoccupied.

Operation of equipment on movement of a westbound train through the track stretch For purposes of illustration it will be assumed that with the equipment in the condition described above a Westbound train accepts the permissive indication displayed by signal 3WS and enters the single track stretch.

When the train enters section ET, the track relay ETTR releases and its contact 62 interrupts the circuit traced above for supplying energy to the green lamp G of signal 3WS and establishes a circuit for supplying energy to the red lamp R of this signal.

In addition, on release of relay ETTR, its contact 46 interrupts the circuit for supplying energy from the decoding transformer 3WDT to relay 3WCTM and it ceases to supply feed-back energy to the rails of section 3T. Accordingly, relay SETR ceases to follow code and relay 3EI-I releases and its contact 53 interrupts the circuit for supplying energy from transformer 2WDT to relay ZWC'IM and it ceases to supply feed-back energy to the rails of section 2T and relay ZETR remains released with the result that relay ZEH releases. On release of relay ZEH its contact 35 interrupts the supply of energy from transformer IWDT to relay IWCTM and it ceases to supply feed-back energy to the rails of section IT and relay IETR remains released with the result that relays IEI-I and IEHP release.

Accordingly, as soon as the westbound train enters section ET, the supply of feed-back energy to the section at the east end of the stretch is cut off with the result that the supply of feedback energy to the other sections is also cut off, and the relay IEHP at the west end of the stretch releases. The relay IEHP may be employed at this time to provide an indication that the single track stretch is occupied.

When the supply of feed-back energy to section 3T is cut off and relay 3EH releases, its contact 54 establishes the circuit for supplying energy to the lamps of signal 2WS and energy is supplied to the green lamp G of signal ZWS over the circuit which includes front contact 55 of relay ZWSR, back contact 54 of relay 3EH, front contact 55 of relay 2WH, and front contact 51 of relay 3D.

Likewise, on release of relay 2EH, its contact 59 establishes the circuit for supplying energy to the lamps of the signal IWS.

This system, therefore, operates so that the lamps of the intermediate signals are normally extinguished and so that on entrance of a train into the stretch the lamps of the signals for the established direction of traffic are lighted.

When the train advances into section 3T, relay 3WTR is shunted and remains released so that energy is no longer supplied through the transformer 3WDT to the relays 3WH and 3WD and they release to maintain the supply of energy to the red lamp R of signal 3WS after section ET is vacated and relay ETTR picks up.

When the train enters section 2T, the relay ZW'IR is shunted and remains released so that relays ZWH and 3D release. On release of relay ZWH, its contact 56 interrupts the circuit traced above for supplying energy to the green lamp G of signal ZWS and establishes the circuit of the red lamp R of this signal so that the signal now displays its red or stop indication.

In addition, when relay 2WH releases, its contact 60 interrupts the circuit for supplying ener y of code frequency to relay 3ECTM and establishes the circuit for supplying energy of 75 code frequency thereto. This circuit includes back contact 60 of relay ZWH, back contact 6| of relay 2WJ, front contact 62 of relay ZWSR, and back contact 63 of relay 3ESR. Accordingly, when section 3T is vacated, this energy feeds to relay 3WTR. and operates it so that relay 3WHP is picked up but relay 3WD remains released. When relay 3WHP picks up, its contact 44 nterrupts the circuit of the red lamp R of signal 3WS and. establishes the circuit of the yellow or caution lamp Y of the signal 3WS.

When relay 3WHP picks up, its contact 4'! establishes the circuit for supplying energy from a secondary Winding of transformer 3WDT to relay 3WCTM and it operates to supply feed-back energy to the rails of section 3T and this energy operates relay 3ETR so that relay 3EI-I picks up. When relay 3EH picks up, its contact 54 interrupts the circuit for supplying energy to the lamps of signal ZWS and the lamps of this signal are extinguished which is proper since it is unnecessary for the signal lamps to be li hted when section 3T is not occupied.

In addition, when relay 3EH picks up, its contact 53 permits energy to be supplied from a secondary winding of transformer 2WDT to relay 2WCTM when section 2T is vacated and relay ZW'I'R is operated by coded energy.

When the train advances into section IT, the relay IWTR is shunted so energy is no longer supplied to relays IWH and 2D and they release with the result that energy is supplied to the red lamp R of signal IWS while the energy supplied to relay ZECTM is changed from 120 to '75 code frequency.

When the train vacates section 2T, the relay 2W'IR responds to the energy of 75 code frequency supplied to the section rails and relay ZWH picks up so that its contact 60 changes the energy supplied to relay 3ECTM from '75 to 120 code frequency, while contact 56 of relay ZWH interrupts the circuit of the red lamp R and establishes the circuit of the yellow lamp Y of signal 2WS With the result that signal ZWS, when lighted, displays its yellow or caution indication.

The energy of 120 code frequency supplied to the rails of section 3T operates the relay 3WTR at a rate such that relay 3WD picks up and its contact 45 interrupts the circuit of the yellow lamp Y and establishes the circuit of the green lamp G of signal 3W8.

In addition, when the train vacates section 2T and relay ZWTR follows coded ener y, impulses of energy are supplied from the transformer 2WDT to relay ZWCTM and it causes feed-back energy to be supplied to the rails of section 2T and this energy operates relay mm to pick up relay 2EH. When relayZEH picks up, its contact 59 interrupts the circuit for supplying energy to the lamps of signal IWS, while contact 35 establishe the'circuit for supplying energy from a secondary winding of transformer IWDT to relay IWCTM.

If, while the train under consideration is in section IT, a second or following train should enter the stretch, the supply of feed-back energy over the rails of sections3T and 2T will be cut off and relays 3EH and ZEH will release to cause the lamps of signals ZWS and IWS to be lighted to thereby provide indications of traffic conditions in advance, while release of relays '3EH and ZEH prevents supply of feed-back energy to the sections in advance of the train and thus prevents picking up of relay IEHP when the first train vacates section IT.

' When the first train enters section WT, the relay WT'IR releases and its contact I! changes the energy supplied to relay IECTM from 120 to 75 code frequency, while contact l5 of relay WTTR interrupts onecircuit and establishes another circuit for supplying energy to the red lamp R of signal IES.

When the train vacates section IT, the coded energy supplied to the section rails feeds to relay IWTR and operates it so that relay IWH picks up to change the energy supplied to relay ZECTM from 75 to 120 code frequency, while contact 65 of relay IWH interrupts the circuit of the red lamp R and establishes the circuit of the yellow lamp Y of signal IWS so that the signal, when lighted, displays its caution indication.

The energy of 120 code frequency supplied to the rails of section 2T operates relay ZWTR at a rate such that relay 3D picks up to cause signal ZWS, when lighted, to display its clear indication, while relay ZWH remains picked up to maintain the supply of energy of 120 code frequency to the relay 3ECTM.

When the train under consideration vacates section I T, and'assuming that no other train has entered the single track stretch, energy is supplied from transformer IWDT to relay IWCTM and it operates to supply feed-back energy to the rails of section IT and this energy operates relay IETR so that relay I EHP. picks up to provide an indication that the single'track stretch is now unoccupied.

If, when the first train vacates section IT, a second or following train has entered the single track stretch, the supply of feed-back energy over the rails of the sections in advance of the train is out off and relay I EHP remains released when section IT is vacated.

From the foregoing, it will be seen that; when the stretch is conditioned for westbound trafiic and a westbound train enters the stretch, the

supply of feed-back energy throughout the stretch in advance of the train is out oil to thereby cause the lamps of the wayside signals in advance of the train to be lighted, while relay IEHP at the west end of the stretch releases to indicate that the. stretch is occupied. In addition, it will be seen that as the train advances through the stretch feed-back energy is supplied to the sections in the rear of the train to extinguish the lamps of the wayside signals, while master code of appropriate code frequency is supplied to these sections to cause the wayside signals to provide the proper indications for a. following train.

Operation ojthe equipment tocowdition stretch for eastbound traffic When it is desired to prepare the stretch for eastbound trafiic, a pick-up circuit is established for relay EMR. This circuit may be established by depressing, the normally open push button EPB, or it may be established by other appropriate means, such as closin of the remotely controlled contact in the circuit of relay EMR. Whenrelay EMB picks up, its contact establishes a stick circuit including back contact 66 of relay IED to maintain relay EMR picked up until relay IED picks up.

When the stretch is conditioned for westbound trafiic, relay WDR is picked up and its contact 68 interrupts the circuit of relay IED and the relay IED is released on picking up of. relay When relay EMR picks up, its contact 10 establishes the circuit including front contact H of relay IEHP and back contact 12 of relay I EJ for supplying energy to therelay EFR and the contacts of relay EFR pick up so that its contact II interrupts the stick circuit of relay WDR and its contacts release with the result that its contact l2 cuts off the supply of energy of '75 or code frequency to the relay IECTM.

Since the circuit of relay EFR includes a front contact of relay IEHP, and as relay IEHP is picked up only when the single track stretch is unoccupied, energy will not be supplied to relay EFR on picking up of relay EMR at a time when the stretch is occupied. Under these conditions, relay EMR remains picked up, and as soon as the stretch is vacant and relay IEHP is picked up, energy is supplied to relay EFR. and it picks up to initiate the traffic reversing function.

When relay EFR picks up, its contact 14 interrupts the circuits controlled by relays IEHP and IED for supplying energy to the lamps of signal IES and establishes a circuit for lighting the red lamp R of signal IE8 and thus insures that this signal will display its red or stop indication until the traffic reversing function is completed.

When relay WDR releases, its contact I61 interrupts the pick-up circuit of relay EMR while its contact I! interrupts one circuit for supplying energy to'the red lamp R of signal IE3 and establishes the circuit including front contact 14 of relay EFR for supplying energy to this signal lamp.

In addition, when relay EFR. picks up, its contact 19 interrupts the circuit of relay IEJ to insure that it remains released at this time.

When relay WDR releases and cuts oil the supply of coded energy to relay IECTM, the supply of master code to the rails of section IT is discontinued so relay IWTR ceases to follow .code and energy is no longer supplied from the transformer IWDT to relay IWCTM and it ceases to supply feed-back energy to the rails of section IT so relay IETR remains released and relays IEH and IEHP release.

When relay IEHP releases, its contact 'H interrupts the previously traced pick-up circuit for relay EFR and establishes a stick circuit to keep the relay picked up as long as relay EMR is picked up. The stick circuit for relay EFR includes its When the relay WDR releases and cuts off the supply of coded energy to the relay IECTM, the contacts of relay IECTM remain released and connect relay IETR across the section rails so that energy supplied over the section rails may pick up the contacts of relay IETR. When relay WDR is released, its contact 23 interrupts the circuit of the holding winding of relay IETR so that if the contacts of relay IETR pick up, they will release as soon as the supply of energy over the section rails is cut off. After relay IECTM ceases to supply master code energy to the rails of section IT, an impulse of feed-back energy may be supplied over the section rails to pick up relay IETR, while on release of relay IETR an impulse of energy is induced in the secondary winding of transformer IEDT which, if supplied to relay IECTM, would pick up its contacts and cause an impulse of energy to be supplied from the battery IWTB to the section rails with the result that the equipment at the right-hand end of section IT would operate to supply an impulse of feed-back energy to the section rails and relay IETR would pick up and release and cause relay IECTM to pick up and repeat the cycle just described. If this condition should develop, the coding operation of relay IETR would keep relay IEI-IP picked up.

The possibility that the condition described above can occur is eliminated since, when relay EFR picks up, its contact 16 interrupts the circuit for supplying energy from the secondary winding of transformer IEDT to relay IECTM. Accordingly, when relay WDR releases and cuts off the supply of coded energy to relay IECTM, the relay IETR remains released and relays I EH and IEHP are certain to release.

When relay IEHP releases, its contact T1 interrupts. the circuit for supplying energy from transformer IEDT to relay IECTM and establishes the circuit for supplying energy of 180 code frequency to relay IECTM. This circuit includes a contact of a code transmitter IBDCT, front contact I8 of relay EFR, back contact T! of relay IEI-IP, and back contact I2 of relay WDR, so the relay IECTM is operated at the 180 code rate and causes energy of 180 code frequency to be supplied to the rails of, section IT.

The energy of 180 code frequency supplied to the rails of section IT operates relay IWTR at a rate such that energy from transformer IWDT picks up relay IWJ, while when relay IWJ picks up, its contact 8]) establishes a circuit including front contact 86 of relay IWH to supply energy to the holding winding of relay IWJ and keep its contacts picked up as long as relay IWH is picked up. When relay IWJ picks up, its contact BI interrupts the circuit of relay ZEJ to insure that it remains released, while contact 82 of relay IWJ interrupts the circuit over which energy is supplied from a secondary winding of transformer ZEDT to relay ZECTM. In addition, on picking up of relay IWJ, its contact 34 interrupts the circuit for supplying energy from transformer IWDT to relay IWCTM and thus prevents operation of this relay to supply feed-back energy to the rails of section IT.

Energy is supplied from transformer IWDT to relay IWCTM in the period from picking up of relay IWH to picking up of relay IWJ and this energy causes relay I WCTM to supply feed-back energy to the rails of section IT. This feed-back energy operates relay IETR, but does not do so long enough to pick up relays IEH and IEHP so relay IEHP remains released and maintains the supply of energy of 180 code frequency to relay IECTM.

When relay IWJ picks up, its contact 39 interrupts the circuit for supplying energy of 75 or code frequency to the relay ZECTM and its contacts remain released so that master code is no longer supplied to the rails of section 2T while the equipment at the east end of the section ceases to supply feed-back energy to the section rails and relay ZETR remains released and relay ZEH releases.

In addition, when relay IWJ picks up, its contact 8 3 interrupts a circuit governed by a contact of relay ZETR for at-times supplying energy to relay IWCTM, While contact 85 of relay IWJ permits energy to be supplied to the pick-up circult of relay ZESR. I

When relay IWJ picks up, its contact 2'! interrupts one stick circuit for relay IWSR, and establishes for relay IWSR a stick circuit including front contact 59 of relay ZEH so that relay IWSR remains picked up until relay 2EH releases.

When relay 2EH releases, its contact 59 interrupts the stick circuit for relay IWSR. established on picking up of relay IWJ and the relay IWSR releases with the result that its contact 26 additionally interrupts the relay stick circuits.

When relay ZEH releases, its contact 8'! interrupts the circuit of relay ZESR so that energy is not supplied to relay ZESR on release of the contacts of relay IWSR.

When relay IWSR releases, a circuit governed by contact 88 of relay IWTR is established for supplying energy to relay ZECTM. This circuit is traced from back contact 88 of relay IWTR, through an asymmetric unit 89, back contact 83 of relay 2EJ, back contact 49 of relay IWSR, and back contact 4| of relay ZESR so the relay ZECTM operates at the same rate as the relay IW'IR, that is, at the code rate. The asymmetric unit 89 included in the circuit just traced prevents the release time of relay ZECTM being prolonged because of the snubbing effect of the primary winding of transformer IWDT and thus insures that relay 2EC'IM will operate to supply impulses of energy of proper length to the rails of section 2T.

In addition, when relay IWSR releases, its contact 83 interrupts the circuit of the holding Winding of relay ZETR so that on subsequent code following operation of relay ZETR energy is not supplied to this winding. I

The energy of 180 code frequency supplied to the rails of section 2T operates relay ZWTR so that energy is supplied through transformer ZWDT to relays ZWH and 2WJ and their contacts pick up. If relay ZWH picks up prior to relay 2WJ, energy is supplied from a secondary win ing of transformer ZWDT over front contact 9| of relay 2WH, back contact 93 of relay ZWJ, front contact 53 of relay 3EH, and front contact 94 of relay ZWSR to relay 2WCTM and it operates to supply feed-back energy to the rails of section 2T. Since the circuit for supplying energy to relay 2WCTM includes a front contact of relay 2WH, energy is not supplied to relay 2WCTM on code following operation of relay ZWTR until relay 2WI-I picks up, and the relay ZWH is of a type the contacts of which are slow to pick up so its contacts pick up little if any in advance of the contacts of relay ZWJ. Accordingly, if relay 2WCTM operates to supply any feed-back energy to the rails of section 2T at this time, it will only supply one or two impulses. This energy will operate relay ZETR to supply energy to relay 2EH, but the relay 2EH is slow to pick up so it probwhich the contacts of relay ZEH are Picked up at this time, if they do become picked up. 1 V

The arrangement just described insures that relay ZESR remains released at this timeso that its contact 4| maintains the circuit governed by contact 88 of relay IWTR for supplying energy of 180 code frequency to relay ZECTM. v

When relay 2WJ picksup, its contact 93 interrupts the circuit for supplying energy from transformer 2WDT to relay 2WCTM and it contacts remain released and do not cause feed-back ,en-

ergy to be supplied to the rails of section 2T.

When relay ZWJ picks up, its, contact 95 establishes a circuit including front contact 96,0f relay ZWH for supplying energy to the holding; winding of relay ZWJ and keeps its contacts picked up as long as relay 2WH is picked up". H

Also when relay vZWJ picks-up, its contact 91 interrupts the circuit including a backcontact of relay 3'ETR for supplying energy/to relay ZWCTM, and thus insures that relay ,2WCTM will remain releasedafter release of relay 2WSR.

and prior to picking up of relay 3ESR;

I'nraddition, when relay 2WJ picks up; its contact B l interrupts the circuit for supplying energy of '75 or 120 co'de frequency'to the relay q3EC'1M and it ceases to supply master code to the rails of section 3T so'the equipment at the right-hand end of section 3T ceases to supply feedeback energy to the section rails and relay 3ETRceases to follow code and relay 3EH releases. At this time, the relays 3WH, 3WHP and 3WD release whereupon relay ZWSR releases and its contact interrupts the relay stick circuits. 1

When relay ZWSR releases, coded energy is supplied to relay 3ECTM over the circuitwhich is traced from back contact I00 of, relay ZWTR,

asymmetric unitllll, back contact 102 'of relay 3EJ, back contact 62 of relay ZWSR, and back contact 63 of relay 3ESR so the relay 3ECTM is operated at the same code rate as the relay ZW'IR, that is, at the 180 code rate. Asshown, energy is supplied to relay 3ECTM over the back contact of relay ZWTR, but it is obvious that, if desirable or necessary to correct for code distortion, the relay 3ECTM might be energized over a front contact of track relay ZWTR, while the corresponding circuits for either direction of traflic at other points in the track stretch may be controlled by either a front or a back contact of a track relay.

When relay 3EC'I'M operates at rate, energy of this code frequency isi'supplied'tc the rails of section 3T and operates relay 3WTR at a rate such that energy is supplied, through the transformer 3WDT to pick up relay 3WJ. The circuit for supplying energy to relay 3WJ includes back contact l05'0f relay WFR and as relay WFR is released at this time energy is suppliedto relay3WJ. -m

When relay 3WJ picks up, its contact Min terrupts the pick-up circuit of relay WFR to inthe 180 code sure that it remains released and thereby makes ineffective an attempt to prepare the stretch for westbound trafilc before the equipment completes its operation to prepare the stretch for eastbound traflic.

When relay 3WJ picks up, its contact I03 interrupts the circuit for supplying energy from transformer 3WDT to relay 3WCTM, whil its contact I06 establishes the pick-up circuit of relay EDR and its contacts pick up with the result that its contact 48 additionally interrupts the circuit for supplying energy from transformer 3WDT to relay 3WCTM and establishes the circuit for supplying to relay 3WCTM energy of or code frequency depending on traffic conditions at the right of section 3T.

In addition, on picking up of relay EDR, its contact 43 interrupts the circuits controlled by relays 3WHP and 3WD for supplying energy to the lamp's'of signal 3WS and establishes the circuit of the red or stop lamp R, of this signal, while contact I01 of relay EDR establishes for the relay EDR a stick circuit which includes back contact I08 of relay WFR. This stick circuit maintains relay EDR picked up after relay 3WJ releases and causes relay EDR to remain picked up until relay WFR is picked up to condition the stretch for westbound trailic. When relay'EDR is picked up, its contact I09 permits .energy to be supplied to the holding winding of relay 3WTR. so that on operation of relayBWTR byfeed-back energy the relay contacts will be maintained picked up for the entire released periods of relay 3WCTM. When relay 3WTR is operated by energy of code frequency, energy is suppliedthrough the transformer3WDT to relay 3WH as well as to relay 3WJ and the relay 3WH may pick up prior to picking up of relay 3WJ. If this occurs, energy is supplied from the transformer 3WDT to relay 3WCTM in the interval from picking up of relay 3WH to picking up of relay 3WJ and the relay 3WCTM will operate to supply feed-back energy to the rails of section 3T. Howevenas explained in connection with section 2T, these impulses of feed-back energy will be too few in number to pick up relay 3ESR. so it remains released and maintains the supply of energy of 180 code frequency to relay 3ECTM.

vAfter relay EDR picks up, the relay 3WCTM is operated by coded energy of '75 or 120 code frequency and causes energy of this code frequency to be supplied to the rails of section 3T. At this time, relay 3ECTM is being operated at the 180 code rate, and because of the difference ods during which impulses of energy supplied from battery 3ETB to the section rails feed over the backcontact of relay 3ECTM and pick up the contacts of the relay 3ETR. Furthermore, becauseof the difference in the code speeds energy will be supplied to relay 3ETR during several successive released periods of the relay SECTM and the relay 3ETR will be operated several times in quick succession with the result that sufiicient energy is supplied through the transformer 3EDT to relay SEH to pick it up and keep it picked up until relay 3ESR picks up.

When relay. 3EH picks up, it establishes the pick-up circuit of relay 3ESR. This circuit includes back contact 55 of relay ZWSR, front contact ll2of relay ZWJ, front contact H4 of relay .3EH,and back contact H5 of relay 3EJ. When .relay 3ESR picks up, its contact H6 establishes a stick circuit for the relay including back con tact H of relay 3EJ so that relay 3ESR ree mains picked up until relay SEJ is picked up which occurs only when the stretch isbeing conditioned for westbound trafilc.

When relay 3ESR picks up, its contact 63 interrupts the circuit governed by contact I00 of relay ZWTR for supplying coded energy to relay 3ECTM, and connects relay 3ECTM to the circuit over which energy is supplied from transformer 3EDT. However, at this time, this circuit is interrupted by contact II8 of relay 2WJ so on picking up of relay 3ESR the relay 3ECTM remains released and ceases to cause energy to be supplied to the rails of section 3T, while the relay 3ETR is constantly connected across the section rails and accurately follows the coded energy supplied to the section rails. Accordingly, relay 3E'H remains picked up, while relay 3D will pick up if the energy supplied-to the rails of section ST is coded at the 120 code-rate. When relay 3ESR picks up, the relay 3D is connected to the transformer 3EDT over a circuit controlled by front contacts Ill and I22 of relay 3ESR and by back contacts I24 and I25 of relay EWSR.

When relay 3ECTM ceases to supply energy to section 3T, the relay 3WTR remains released and relay 3WH releases, and relay 3WJ also releases if it has not already released because of irregular operation of relay 3WTR after relay 3WCTM is operated by energy of 75 or 120 code frequency. When relay SWJ releases, its contact I06. interrupts the pick-up circuit of relay EDR but this relay is maintained picked up by energy supplied over its stick circuit and therefore maintains the supply of coded energy to relay 3WCTM. In addition, on release of relay 3WJ its back contact IE3 is closed but as relay EDR is picked up energy cannot be supplied from transformer 3WDT to relay 3WCTM.

On release of relay 3WH, relay 3WHP releases and its contact I21 interrupts the pick-up circuit of relay WFR to thereby prevent picking up of this relay and thus renders ineffective an attempt to prepare the stretch for westbound traffic until operation of the equipment to prepare the stretch for eastbound traffic is complete.

When relay SESR picks up, energy of 120 code frequency is supplied to relay 2WCTM over the circuit which includes front contact I30 of relay 3EI-I, back contact I3I of relay 3EJ, front contact :32 of relay 3ESR, and back contact 94 of relay 'JWSR so the relay 2WCTM operates to supply energy of 120 code frequency to the rails of section 2T.

When relay 3WSR picks up, its contact 63 connects relay 3ECTM to the circuit over which energy is supplied from a secondary winding of transformer 3EDT, but as long as relay ZWJ is picked up its contact IIB interrupts this circuit and prevents supply of energy to the relay 3ECTM. As explained above, when relay ZWJ picks up, it establishes for itself a stick circuit including front contact 96 of relay ZWH. Accordingly, when relay 2WCTM is operated by coded energy and operation of relay ZWTR becomes irregular, relay ZWJ is maintained picked up by energy supplied to its holding winding, and contact IIB of relay 2WJ prevents the supply of energy from transformer 3EDT to relay 3ECTM and relay 3ECTM does not operate to supply feed-back energy to the rails of section 3'1 and relays 3WH and 3WHP remain released.

The energy of 120 code frequency supplied; to the rails of section 2T as a result of operation of relay 2WCTM feeds to relay ZETR during released periods of relay ZECTM and operates relay 2ETR so that relay 2EH picks up and estabilshes the pick-up circuit for relay ZESR. When relay ZEH picks up, energy is supplied to relay ZESR over the circuit which includes back contact 26 of relay IWSR, front contact of relay IWJ, front contact 87 of relay ZEH, and back contact I33 of relay 2EJ, while when relay ZESR picks up, its contact I34 establishes a stick circuit including back contact I33 of relay 2EJ to maintain the relay picked up until relay ZEJ is picked up.

When relay ZESR picks up, the relay 2D is connected over back contacts 29 and 32 of relay IWSR and front contacts 39 and 3| of relay ZESR t the transformer 2EDT, and as relay ZETR is operated at the code rate the contacts of relay ZD pick up.

When relay 2ESR picks up, its contact 4| interrupts the circuit including back contact 88 of relay IWTR for supplying energy to relay ZECTM and connects'relay ZECTM to the circuit over which energy is supplied from transformer ZEDT to relay 2ECTM. However, on picking up of relay ZESR, the circuit leading from transformer 2EDT is interrupted bycontact 82 of relay IWJ so energy is'not supplied to relay 2EC'IM and it remains released and does not supply energy to the rails of section 2T. Accordingly, relay ZWTR remains released and relay ZWH releases with the result that. its contact I35 prevents supply of energy from transformer 3EDT to relay 3ECTM and it remains released. In addition, on release of relay 2WH its contact 96 interrupts the stick circuit for relay ZWJ and its contacts release, but contact I35 of relay ZWH interrupts the circuit for supplying energy from transformer ZEDT to relay 3ECTM before contact II8 of relay 2WJ establishes this circuit so relay 3ECTM remains released. As a result relays 3WH and 3WHP remain released and contact I21 of relay 3WHP interrupts the pick-up circuit of relay WFR to thereby render ineffective an attempt to prepare the stretch for westbound traffic before the equipment completes its operation to prepare the stretch foreast-bound traffic.

When relay ZESR picks up, the circuit for supplying traffic governing coded energy to relay IWCTM is established and includes a contact of code transmitter IZHCT, front Contact I 40 of relay 2EH, back contact I4I of relay ZEJ, front contact I42 of relay ZESR, and back contact 36 of relay IWSR, Accordingly, relay IWCTM operates to supply energy of 120 code frequency to the rails of section IT and this energy feeds to relay IETR during the released periods of relay IEC'IM so that energy is supplied through the transformer IEDT to the relay IEH and it picks up to establish the circuit of relay IEI-IP and the contacts of relay IEHP pick up with the result that contact 11 interrupts the supply of energy of code frequency to the relay IECTM and connects relay IEC'IM to the circuit over which energy is supplied from a secondary winding of transformer IEDT. However, at this time this circuit is interrupted by contact 16 of relay EFR. so that on picking up of relay IEHP the relay IECTM is not operated by energy supplied from transformer IEDT, but remains released and constantly connects relay IETR across the section rails. Accordingly, relay I ETR will accurately follow the energy of 120 code frequency supplied over the rails of section IT and energy is supplied through the transformer I EDT and the resonant rectifier unit I20DU to the relay IED and its contacts pick up with the result that contact 66 interrupts the stick circuit for relay EMR. and its contacts release so that contact 65 additionally interrupts the relay stick circuit.

When relay IEHP picks up, its contact II transfers control of relay EFRfrom its stick circuit to its pick-up circuit, while on release of relay EMR its contact III interrupts the pick-up circuit of relay BER and its contacts release so that contact I3 interrupts the relay stick circuit and contact 18 interrupts the circuit over which energy of 180 code frequency was supplied to relay I ECTM.

Inaddition, when relay EFR releases, its contact I4 interrupts the circuit of the red lamp R of signal IES and establishes the circuit controlled by relays IEHP and IE1) for supplying energy to the lamps of signal IES. At this time relays IEHP and IED are picked up so energy is supplied over front contact I6 of relay W'I'IR, back contact I! of relay WDR, back contact 14 of relay EFR, front contact I44 of relay IEHP, and front contact I45 of relay IED to the green lamp G of signal IES and this signal therefore provides a green or clear indication to indicate that the single track stretch is conditioned for eastbound traflic. It will be seen, therefore, that when the established direction of traffic is changed from eastbound to westbound the signal IES governing entrance of eastbound trains into the track stretchis caused to display its red or stop indicationduring operation of the equipment to change the direction of trafiic and that when the trafiic reversing function is completed the signal iES displays an indication controlled by traflic in advance.

When relay EFR releases, its contact I9 establishes the circuit of relay IEJ to permit the equipment to be operated to condition the stretch for westbound trafiic, while contact 16 establishes the circuit for supplying energy from transformer I EDT to relay IECTM. This circuit includes front contact I46 of relay WTTR, back contact 16 of relay EFR, back contact I41 of relay IEJ, front contact I! of relay IEHP, and back contact I2 of relay WDR. Accordingly, the relay IECTM now operates to' supply impulses of feed-back energy to the rails of section IT. I

It will be seen that operation of relay IECTM to supply energy of 180 code frequency to the rails of section IT is discontinued when relay IEHP picks up, while operation of relay IECTM to supply feed-back energy to the section rails is not initiated until relayEFR releases, and release of relay EFR is not initiated until relay EMR. releases, while release of relay EMR is not initiated until relay' IED picks up. Accordingly, there is a considerable period from the time relay IECTM ceases to supply energy of 180 code frequency to the rails of section IT and the time at which it starts to operate to supply feed-back energy to the section rails. This period is long enough to insure that relays IWJ and IWH will release to interrupt the circuit of the holding winding of relayIWJ so that the contacts of relay I WJ 'are released.

n operation of relay IECTM to upply feedback energy to the rails of section IT, relay IWTR is operated and energy is supplied through transformer IWDT to pick up relay IWH. At this time,- contact I48'of relay 2ESR establishes the circuit for supplying energy to theholding winding of relay IWTR to thereby cause the contacts of relay IWTR, when picked up, to remain picked up for the entire released period of the contacts of relay I WCTM.

When relay IWH picks up, energy is supplied from transformer 2EDT to relay ZEC'I'M over the circuit which includes front contact I50 Or relay ZEH, back contact II of relay 2EJ, back contact 820i relay IWJ, front contact I52 of relay IWH,

, and front contact M of relay ZESR. Accordingly, relay 2ECTM operates to supply feed-back energy to the rails of section 2T and this energy operates relay 'ZWTR to pick up relay ZWH, while on picking up of relay 2WH energy is supplied from transformer 3EDT to relay 3ECTM over a circuit similar to that just traced for relay ZECTM, and relay SECTM operates to supply feed-back energy to the rails of section 3T. This energy operate relay 3WTR to pick uprelay 3WH and thus pick-up relay 3WI-IP, 'while on picking up of relay 3WHP suitable means, not shown, may be operated to indicate that the track stretch is unoccupied, while this indication may also serve as an indication that the traific reversing function is complete and that the stretch is prepared for eastbound traflic.

When the traflic reversing function is completed, relays IWH and ZWH are picked up so energy i not supplied to the lamps of signals ZES and 31518 and these signals are dark at this time which is proper since the stretch is vacant and there is no need for the signals to be lighted.

The operation of the equipment to change the stretch from eastbound to westbound trafiic is similarto that just traced for changing from westbound to eastbound tramc and a detailed explanation of the operation of the equipment at these times is unnecessary,

If, after the stretchhas been prepared for eastbound traflic, an eastbound train accepts the permissive indication displayed by signal IE8 and enters the single track stretch, relay W'ITR will release so that its contact I6 cuts oif the supply of energy to the green lamp G of signal IES and establishes thecircuit of the red lamp R of this signal. In addition, on release of relay WTTR its contact I46 interrupts the circuit for supplying energy from transformer IEDT to.

relay IWTR remains released and relay IWH releases with the result that energy is supplied to the green lamp G of signal ZES over the circuit which includes front contact I34 of relay 2ESR, back contact I55 of relay IWH, front contact I53 of relay ZEH, and front contact I54 of relay 2D so that the signal 2E3 displays its green or clear indication.

On release of relay IWH its contact I52 interrupts the circuit for supplying energy from transformer 2EDT to relay ZECT'M and it ceases to supply feed-back energy to the rails of section 2T and relay 2WH releases to establish the circuit for supplying energy to the lamps of signal 3E8, and to interrupt the supply of energy from transformer 3EDT to relay 3ECTM. Accordingly, relay 3ECTM remains released and ceases to supply feed-back energy to the rails of section 3T so that relay SWTR'ceases to follow code and relays 3WH and 3WHP release to prevent picking up of relay WFR and thus render ineffective an attempt tochange the established direction of trafiic. If desired, release of relay 3WI-IP may be employed to indicate that the single track stretch is occupied.

As the eastbound trainproceeds through the track stretch the equitunent operates in manner similar to that'described in connection with movement of a westbound train through the track stretch and a detailed description of the operation of the equipment is unnecessary. As each section is vacated by the eastbound train, feed-back energy is supplied over the section rails to operate the equipment at the exit end of the section to extinguish the lamps of the wayside signal for the adjacent section in advance and to condition the equipment for the section in advance to operate to supply feed-back energy over the section rails when that section is vacated. As soon as the train vacates section 3T, relays 3WH and 3WHP pick up to permit ener y to be supplied to relay WFR and thus permit the established direction of traffic to be reversed if desired.

It will be seen that the supply of feed-back energy to the stretch is cut off as soon a a train passes the headblock signal and enters the detector section at the existing entrance end of the stretch so that the equipment at the exit end of the stretch operates immediately to indicate that the stretch is occupied and to prevent interruption with the established direction of traffic.

It will be seen also that reversal of the established direction oi traflic may be initiated while the detector section at the egrit end of the stretch is occupied. Accordingly, on movement of a train in one direction through the stretch, the change in the established direction of traffic may be effected with a minimum of delay, While a change'in the established direction of traffic can be initiated before the detector section is vacated, the headblock signal governing entrance of trains into the track stretch at the new entrance end will not display a permissive indication until the detector section 'is vacated since this signal is controlled by the track relay of the detector section. This prevents clearing of the headblock signal even though operation of the equipment w reverse the established direction of traffic should be completed before the detector section is vacated.

This system is arranged so that when th stretch is conditioned for either direction or traffic, depressing of the push button at the existing entrance end oi the stretch has no effect. When the stretch is conditioned for'westbound traffic, the relay EDR is releasedand its contact IBQ interrupts the pick-up circuit for rela WMR so that, if the push button WPB should be depressed or the associated remotely controlled con? tact be closed, it would have no effect and relay WMR would remain released, while the equipment would continue to function in the normal manner. Similarly, whenthe' stretch is conditioned for eastbound traffic, relay WDR is released and its contact I61 interrupts the pickeup circuit of relay EMR so that, if the push button EPB should be depressed, the relay EMR will remain released and the equipment will continue to function in the normal manner.

As explained above, when the established direction of name is to be changed, the supply of traffic governing energy of 75 or 120 code 'frequency to the section at the existing exit end of the stretch is cut off. and energy of 180. code frequency is substituted therefor." In addition, as explained above, when the stretch is occupied, the suppl of feed-back energy over the rails of the sections in advance of the, train is discontinued and the equipment at the exit end of the s e ch pe ates t Preven the supp y of ener y of code frequency to the stretch and thus renders ineffective an attempt to reverse the established direction of tra-fiic.

However, if for any reason the equipment is not functioning as intended and traflic reversin energy of 180 code frequency should be supplied to the exit end of the stretch When the stretch is occupied, it would not condition the stretch for movement of trains in the direction opp site to that of the train present in the stretch and, therefore, would not create a hazardous condit nn- For purposes of illustration, it will be assumed that the stretch is conditioned for Westbound ffi and that a westbound train has entered the stretch and is present in section 3T, As the stretch i assumed to be prepared for westbound traific, the westbound directional stick relays IWSR and ZWSR are picked up, while relay WDR is also picked up. As section 3'; I is assumed to be occupied, the suppl of feed-back energy over the rails of sections 2T and IT is cut off and relays IEH and IEHP are released. Under these conditions, contact H of rela IEHP interrupts the pick-up circuit for relay EFR and relay EFR should remain released to maintain the stick circuit for relay WDR and interrupt the circuit for supplying energy of 180 code frequency to relay IECTM.

If, as a result'of some defect in the equipment, rela EFR should become picked up, its contact [2 will interrupt the stick circuit of relay WDR and its contacts will release and energ of 180 code frequency may be supplied to the relay IECTM with resultant supply of energy of this code frequency to relay IWTR so that relay IWJ picks up.

When relay IWJ picks up, its contact 39 cuts off the supply of traffic governing coded energy to relay ZECTM and thus causes it to cease to supply energ to the rails of section 2T so that the equipment at the right-:hand end of section 2T causes the signal ZWS to display its stop indication, while the supply of feed-back energy over the rails of section 2T is cut off if it has not already been discontinued. Accordingly, relay EEH releases and its contact 59 interrupts the stick circuit of relay IWSR and it releases so that relay ZECTM is operated by energy supplied over back contact 88 of relay IWTR and energy of 180 code frequency is now supplied to the rails of section 2T. This energy operates relay ZWTR to pick up relay ZWJ. and thus cause release of relay ZWSR so that its contact 55 interrupts the circuit of the lamps of signal 2W8, while relay 3ECTM is operated by energ supplied over back contact I00 of relay ZWTR,

As section 3T is assumed to be occupied, operation of relay 3ECTM is without effect and relay 3EH remains released and does not establish the pick-up circuit for relay 3ESR. Accordingly, relay 3 ESR remains released and its contact I32 does not establish the circuit for supplying coded energy to relay ZWCTM so it remains released and coded energy is not supplied to the east end of section 2 T so relay ZESR, remains released and does not establish the circuit for supplying coded energy to relay I WCTM, Coded energy, therefore, is not supplied to the rails of section IT and relays IEH and IEHP remain released to maintain the supply of energy of 180 code irequencyto relay I ECTM and to prevent the dis play oi a permissive indication by signal IES,

It w l e p nt t e e ore, that if energy of 180 code frequency should be supplied to the exit end of the stretch when the stretch is occupied, it will not cause the equipment to authorize entrance into the stretch of a train moving in the opposite direction to that'already presentin the stretch. Furthermore, the energy of 180 code.

frequency supplied to the stretch while it is occupied causes release of the directional stick relays for the established direction of trafiic, thereby discontinuing the display of permissive indications by the signals governing movement of the train present in the track stretch. The absence of indications by the wayside signals will cause.

the train in the stretch to stop or to proceed at reduced speed, which is proper when the equip. ment is not functioning as intended.

The equipment operates in a similar manner if, while the stretch is conditioned for eastbound.

trafiic and is occupied, energy of 180 code frequency is supplied to the east end of the stretch and a detailed explanation of the operation of the equipment is unnecessary. a

It will be seen also that the normal operation of the equipment is such that, when the stretch is conditioned for either direction of traific. the appropriate directional stick relays are picked up to maintain this direction of traflic, while the stick circuits for these relays are interrupted only on supply of the special. traflic reversing code through the track stretch. This prevents inter ference with the established direction of trafiic by unusual conditions such as temporary shunt ing of the rails of a track section at an intermediate point in the track stretch.

In addition, it will be seen that the system is arranged so that once the traflic reversing energy of 180 code frequency is supplied to the stretch, the supply of this energy is maintained and cannot be interrupted until the traffic reversing function is complete so there is no possibility that the established direction of traflic will dis turbed Without the new direction of traffic being established. I

Furthermore, the system is arranged so that establishment of the new direction of traflic is not begun until the special trafiic reversing energy has been transmitted throughout the entire stretch so there is no possibility that the new direction of traffic will be established in a part of the stretch without being established in'the entire stretch. I

Modification shown in Fig. 2 i

As explained above, the system shown in Fig. l. is arranged so that when the stretch isconditioned for westbound traific the relay EMR may. be picked up regardless of whether the stretchis occupied or not. If thestretch is vacant when relay EMR picks up, reversal of the established direction Of traflic is initiated immediately. However, if, when relay EMR picks up, the1stretch is:

prevent: picking up of relay WMR when the stretch is occupied by an eastbound train.

-;The'.,ope ration of the. modification shownlin Fig. 2, therefore, is such that, if traffic conditions prevent reversal of the established traflic direction at the time the reversal is attempted, the reversal will nottake place without further attention from an operator when trafiic conditions change so that it is permissible.

Although I have herein shown and described only one form of railway signaling system embodying my invention, together with a modification thereof which I may employ, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is: t

1. In combination, a stretch of single track railway through which trafilc may move in either direction, the rails of'said stretch being divided into a plurality of track sections, two sets 01 coded track circuit apparatus for each section, one for each direction of trafiic, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, trafiic direction control means effective at times to cause traffic in each section to be controlled by said coded track circuit apparatusfor one direction of traffic and effective at other times to cause traffic in the section to be controlled by said coded track circuit apparatus for the other direction of traffic, means effective when the direction of trafiic in the stretch has been established to supply to the corresponding exit end of each section energy of a trailic governing code frequency, means at each end of the stretch for controlling the directionof traflic movements through the stretch comprising means for cutting off the supply of energy of traflic governing code frequency to the railsof the section at that end of the stretch and for supplying thereto traflic reversing energy of a distinctive code frequency, means responsive to traflic reversing energy supplied to the track rails at the end of the stretch for causing energy of causing traflic governing energy to be supplied to the rails'of the section at that end of the stretch, means responsive to such traflic governing energy supplied to the rails at said end of the stretch for progressively cutting oif the supply of traflic 6, reversing energy to the successive sections in said stretch and for causing the supply of traffic governing energy to be repeated through the successive sections to the end of the stretch and including means responsive to the supply of traffic governing energy over the rails of each section for causing the traffic direction control means to esinto a plurality oftrack sections, two sets of coded track circuit apparatus for each section, one for each direction of trafiic, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, traffic direction control means comprising a first and a second stick relay at each junction between sections in said. stretch, said traffic direction control means bein effective when said first stick relays are picked up and said second stick relays are released to cause trafiic in each section to be controlled by said coded track circuit apparatus for one direction of traflic and being effective when said first stick relays are released and said second stick relays are picked up to cause traflic in each section to be controlled by said coded track circuit apparatus for the other direction of traffic, means effective when the direction of traffic in the stretch has been established to supply to the corresponding exit end of each section energy of a trafiic governing code frequency, means at each end of the stretch for controlling the direction of traific movements through the stretch comprising means for cutting off the supply of energy of traffic governing cod frequency to th rails of the section at that end of the stretch and for supplying thereto trafiic reversing energy of a distinctive code frequency, means responsive to traffic reversing energy supplied to the track rails at the end of the stretch for causing the energized directional stick relays to release successively to thereby cancel the established direction of traflic and to cause energy of this code frequency to be supplied to the corresponding ends of the remaining sections of the stretch, means at each end of the track stretch responsive to the trailic reversing energy supplied from the opposite end of the stretch for causing trafiic governing energy to be supplied to the rails of the section at that end of the stretch, means responsive to such trafiic governing energy supplied to the rails at said end of the stretch for progressively picking up the directional stick rela s which establish the new direction of traiiic to thereby cut off the sups ply of trailic reversing energy to the successive sections in said stretch and to cause the supply of trafiic governing energy to be repeated through the successive sections to the end of the stretch, and means at each end of the stretch responsive to the traffic governing energy supplied over the rails of the stretch to discontinue the supply of traffic reversing energy thereto and for controlling a signal governing entrance of trafiic into the stretch.

3. In combination, a stretch of single track railway through which trafiic may move in either direction, the rails of said stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, one for each direction of traflic, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, traffic direction control means effective at times to cause traffic in each section to be controlled by said coded track circuit apparatus for one direction of trafiic and effective at other times to cause trafiic in the section to be controlled by said coded track circult apparatus for the other direction of traffic, means effective when the direction of traflic in the stretch has been established to supply to the corresponding exit end of each section energy of a traflic governing code frequency, meansat each end of the stretch for controlling the direction of traffic movements through the stretch comprising means for cutting off the supply of energy of traffic governing code frequency to the rails of the section at that end of the stretch and for supplying thereto traffic reversing energy of a distinctive code frequency, means responsive to trafiic reversing energy supplied to the track rails at the end of the stretch for causing energy of this code frequency to be supplied successively to the corresponding ends of the remaining sections of the stretch, means responsive to the supply of said traffic reversing energy over the rails of each section for causing the traflic direction control means to cancel the established direction of trafiic in such section, means at each end of the track stretch responsive to the trafiic reversing energy supplied from the opposite end of the stretch for causing traflic governing energy to be supplied to the rails of the section at that end of the stretch, means responsive to such traffic governing energy supplied to the rails at said end of the stretch for progressively cutting off the supply of traflic reversing energy to the successive sections in said stretch and for causing the supply of traffic governing energy to be repeated through the successive sections to the end of the stretch and including means responsive to the supply of traflic governing energy over the rails of each section for causing the trafllc direction control means to establish the new direction of trafiic in such section, means at each end of the stretch responsive to the traffic governing energy supplied over the rails of the stretch to discontinue the supply of traific reversing energy thereto, and means at each end of the stretch governed by traffic in the stretch for preventing interruption of the supply of traffic governing energy to the rails of the stretch at that end of the stretch while the stretch is occupied.

4. In combination, a stretch of single track railway through which traific may move in either direction, the rails of said stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, one for each direction of traffic, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, trafiic direction control means effective at times to cause traflic in each section to be controlled .by said coded track circuit apparatus for one direction of traflic and effective at other times to cause traific in the section to be controlled by said coded track circuit apparatus for the other direction of trafiic, means effective when the direction of traific in the stretch has been established to supply to the corresponding exit end of each section master code energy of a, traffic governing code frequency and tosupply impulses of feed-back energy to the track rails entrance end of the track stretch, means responsive to feed-back energy supplied to the track rails at the entrance end of the stretch for causing feed-back energy to be supplied successively to the entrance end of the remaining sections of the stretch, means at each end of the stretch for controlling the direction of traffic movements through the stretch comprising means for cutting off the supply of energy of trafiic governing code frequency to the rails of the section at that end of the stretch and for supplying thereto trafiic reversing energy of a distinctive code frequency, means responsive to traflic reversing energy supplied to the track rails at the end of the stretch for causing energy of this code frequency to be supplied successively to the corresponding ends of the remaining sections of the stretch, means responsive to the supply of said traffic reversin energy over the rails of each section for causing the traflic direction control means to cancel the established direction of traffic in such section, means at each end of the track stretch responsive to the traific reversing energy supplied from the opposite end of the stretch for causing traffic governing energy to be supplied to the rails of the section at that end of the stretch, means responsive to such traflic governing energy supplied to the rails at said end of the stretch for progressively cutting off the supply of traffic reversing energy to the successive sections in said stretch and for causing the supply of traffic governing energy to be repeated through thesuccessive sections to the end of the stretch and including means responsive to the supply of traffic governing energy over the rails of each section for causing the traffic direction control means to establish the new direction of traffic in such section, means at each end of the stretch responsive to the traffic governing energy supplied over the rails of the stretch to discontinue the supply of traflic reversing energy thereto, and means at each end of the stretch responsive to feed-back energy supplied over the rails of the stretch.

5. In combination, a stretch of single track railway through which traffic may move in either direction, the rails of said stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, one for each direction of traflio, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, traffic direction control means efiective at times to cause traffic in each section to be controlled by said coded track circuit apparatus for one direction of traific and effective at other times to cause traffic in the section to be controlled by said coded track circuit apparatus for the other direction of traffic, means effective when the direction of traffic in the stretch has been established to supply to the corresponding exit end of each section master code energy of a trafiic governing code frequency and to supply impulses of feed-back energy to the track rails entrance end of the track stretch, means responsive to feed-back energy supplied to the track rails at the entrance end of the stretch for causing feed-back energy to be supplied successively to the entrance end of the remaining sections of the stretch, means at each end of the stretch for controlling the direction of traffic movements through the stretch comprising means effective only when feed-back energy is being received over the track rails at that end of the stretch for cutting off the supply of energy of traffic governing code frequency to the rails of the section at that end of the stretch and for supplying thereto traffic reversing energy of a distinctive code frequency, means responsive to traffic reversing energy supplied to the track' rails at the end of the stretch for causing energy of this code frequency to be supplied successively to the corresponding ends of the remaining sections of the stretch, means responsive to the supply of said traflic reversing energy over the rails of each section for causing the traflic direction control means to cancel the established direction of traffic in such section, means at each end of the track stretch responsive to the traffic reversing energy supplied from the oppositev end of the stretch for causing traific governing energy to be supplied to the rails of the section at that end of the stretch, means responsive to such traffic governing energy supplied to the rails at said end of the stretch for progressively cutting oif the supply of traffic reversing energy to the successive sections in said stretch and for causing the supply of trafiic governing energy to be repeated through the successive sections to the end of the stretch and including means responsive to the supply of traffic governing energy over the rails of each section for causing the traffic directicn control means to establish the new direction of traffic in such section, and means at each end of the stretch responsive to the traiflc governing energy supplied over the rails of the stretch to discontinue the supply of traflic reversing energy thereto. 7

6. In combination, a stretch of single track railway through which traflic may move in either direction, the rails' of said stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, one for each direction of traffic, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, traific direction control means effective at times to cause traffic in each section to be controlled by said coded track circuit apparatus for one direction of traflic and effective at other times to cause traffic in the section to be controlled by said coded track circuit apparatus for the other direction of traffic, means effective when the direction of traffic in the stretch has been established to supply to the corresponding exit end of each section master code energy of a traffic governing code frequency and to supply impulses of feed-back energy to the track rails entranc end of the track stretch, means responsive to feed-back energy supplied to the track rails at the entrance end of the stretch for causing feed-back energy to be supplied successively to the entrance end of the remaining sections of the stretch, a control relay at each end of the stretch for controlling the direction of traffic movements through the stretch and having contacts movable between a first and a second position, each such control relay being effective when its contacts are in their second position to cause traffic governing energy to be supplied to the rails of the stretch at the corresponding end of the stretch and being effective when its contacts are in their first position to permit traflic reversing energy of a distinctive code frequency to be supplied to the rails of the stretch at the corresponding end thereof,means at each end of the stretch effective only when feed-back energy is being received over the track rails at that end of the stretch for moving thecontacts of the control relay at that location from their second to their-first position, means responsive to tra'ificfrevers'ing energy supplied to the track rails at the endof the stretch for causing energy of this code frequency to be supplied successively to the corresponding ends of the remaining sections of the stretch, means responsive to the supply of said traflic reversing energy over the rails of each section for causing the traffic direction control means to cancel the established direction of traffic in such section, means at each end of the track stretch responsive to the traiiic reversing energy supplied from the opposite end of the stretch for moving the contacts of the control relay at that end of the stretch from their first to their second position, means responsive to the traffic governing energy supplied to the stretch at the end opposite to that at which traffic reversing energy is supplied to the stretch for progressively cutting off the supply of trafiic reversing energy to the successive sections in said stretch and for causing the supply of traffic governing energy to be repeated through the successive sections to the end of the stretch and including means responsive to the supply of traffic governing energy over the rails of each section for causing the trafiic direction control means to establish the new direction of traffic in such section, and means at each end of the stretch responsive to the traffic governing energy supplied over the rails of the stretch to discontinue the supply of traific reversing energy thereto.

7. In combination, a stretch of single track railway through which traffic may move in either direction, the rails of said stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, one for each direction of traffic, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, traffic direction control means comprising a first and a second stick relay at each junction between sections in said stretch, said traffic direction control means being effective when said first stick relays are picked up and said second stick relays are released to cause traffic in each section to be controlled by said coded track circuit apparatus for one direction of trafiic and being effective when said first stick relays are released and said second stick relays are picked up to cause traffic in each section to be controlled by said coded track circuit apparatus for the other direction of traffic, means effective when the direction of traffic in the stretch has been established to supply to the corresponding exit end of each section master code energy of a traffic governing code frequency and to supply impulses of feed-back energy to the track rails at the entrance end of the stretch, means responsive to feed-back energy supplied to the track rails at the entrance end of the stretch when the direction of traffic in the stretch has been established to cause feed-back energy to be supplied successively to the entrance ends of the remaining sections of the stretch, means at each end of the stretch for controlling the direction of traffic movements through the stretch comprising means for cutting off the supply of master code energy of traffic governing code frequency to the rails of the section at that end of the stretch and for supplying thereto trafiic reversing energy consisting of master code energy of a distinctive code frequency, means responsive to traflic reversing energy supplied to the track rails at the end of the stretch for causing the energized directional stick relays to release successively to thereby cause the master code energy supplied to the corresponding ends of the remaining sections of the stretch to be changed from a traffic governing frequency to the trafiic reversing frequency and to cut off the supply of feed-back energy to each of the sections, means at each end of the stretch responsive to the traific reversing energy supplied from the opposite end of the stretch for causing master code energy of a trafiic governing frequency to be supplied to the rails of the section at that end of the stretch, means responsive to such trafiic governing energy supplied to the rails at said end of the stretch for progressively picking up the directional stick relays which establish the new direction of traffic to thereby out 01f the supply of traffic reversing energy to the successive sections in said stretch and to cause the supply of traffic governing energy to be repeated through the successive sections to the end of the stretch, and means at each end of the stretch responsive to the trafiic governing energy supplied over the rails of the stretch to discontinue the supply of traihc reversing energy thereto and to cause impulses of feed-back energy to be supplied to the rails of the track stretch at that end thereof.

8. In combination, a stretch of single track railway through which trafiic may move in either direction, the rails of said stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, one for each direction of traffic, each set comprising a code following relay located at the corresponding entrance end of the section responsive to coded energy supplied over the track rails from the other end of the section, traffic direction control means comprising a first and a second stick relay at each junction between sections in said stretch, said trafiic direction control means being effective when said first stick relays are picked up and said second stick relays are released to cause traffic in each section to be controlled by said coded track circuit apparatus for one direction of trailic and being effective when said first stick relays are released and said second stick relays are picked up to cause traflic in each section to be controlled by said coded track circuit apparatus for the other direction of traffic, means effective when the direction of traffic in the stretch has been established to supply to the corresponding exit end of each section master code energy of a traffic governing code frequency and to supply impulses of feed-back energy to the track rails at the entrance end of the stretch, means responsive to feed-back energy supplied to the track rails at the entrance end of the stretch when the direction of trafiic in the stretch has been established to cause feedback energy to be supplied successively to the entrance ends of the remaining sections of the stretch, means at each end of the stretch for controlling the direction of traffic movements through the stretch and comprising means effective only when feed-back energy is being received over the track rails at that end of the stretch for cutting off the supply of master code energy of trafiic governing code frequency to the rails of the section at that end of the stretch and for supplying thereto trafiic reversing energy consisting of master code energy of a distinctive code frequency, means responsive to traffic reversing energy supplied to the track rails at the end of the stretch for causing the energized directional stick relays to release successively to thereby cause the master code energy supplied to the corresponding ends ,of the remaining sections of the stretch to be changed from a traffic governing frequency to the traffic reversing frequency and to cut off the supply of feed-back energy to each of the sections, means at each end of the stretch responsive to the traffic reversing energy supplied from the opposite end of the stretch for causing master code energy of a traffic governing frequency to be supplied to the rails of the section at that end of the stretch, means responsive to such traflic governing energy isup plied to the rails at said end of the stretch for progressively picking up the directional stick relays which establish the new direction of traffic to thereby cut off the supply of traffic reversing energy to the successive sections in said stretch and to cause the supply of trafiic governing energy to be repeated through the successive sections to the end of the stretch, and'means at each end of the stretch responsive to the traflic governing energy supplied over the rails of the stretch to discontinue the supply of traffic reversing energy thereto and to cause impulses of feed-back energy to be supplied to the rails of the track stretch at that end thereof.

9. In combination with a stretch of track over which traffic may move in either direction, said stretch being divided into a plurality of track sections, means effective when traffic in said stretch has been established in either direction to supply master code energy of a traffic governing code frequency to the corresponding exit end of each track section, traiiic reversing means at each end of the stretch for changing that end of the stretch from an exit to an entrance end and comprising means to discontinue the supply of master code energy of a traffic governing frequency to the rails of the stretch and for supplying thereto tramc reversing energy comprising master code energy of a distinctive code frequency, means for each section effective on the supply of traffic reversing energy thereto at either end to supply energy of this code frequency to the rails of the adjacent section to thereby cause energy of this code frequency to be cascaded to the existing entrance end of the stretch, means at each end of the stretch operative on the supply thereto of traffic reversing energy over the rails of the track stretch to supply master code energy of a traffic governing code frequency to the track rails atthat end of the stretch, means for each section operative on the supply thereto of traffic governing energy at the new exit end thereof to cut off the supply of traiiic reversing energy .to the section rails and to cause traflfic governing energy to be supplied to the rails of the adjacent section to thereby cause the supply of trafiic reversing energy to be progressively cut off and to cause the supply of traffic governing energy to be cascaded to the new entrance end of the stretch, and means at each end of the stretch responsive to the supply of traffic governing energy over the rails of the stretch for controlling entrance of tramc into the stretch.

'10. In combination with a stretch of track over which traffic may move in either direction, said stretch being divided into a plurality of track sections, means effective when traffic in said stretch has been established in either direction'to supply master code energy of a traffic governing code frequency to the corresponding exit end of each section and to supply impulses of feed-back energy to the corresponding entrance end of the stretch and to cause the supply of feed-back energy to be repeated through successive track sections to the corresponding exit end of the stretch provided the stretch is vacant, traffic reversing means at each end of the stretch for changing that end of the stretch from an exit to an entrance end and comprising means effective only when feed-back energy is being received at the end of the stretch to discontinue the supply of master code energy of a trafiic governing frequency to the rails of the stretch and for supplying thereto trafilcreversing energy comprising master "code energy of a distinctive code frequency, means for each section effective on the supply of traffic reversing energy thereto at either end to supply energy of this code frequency to the rails of the adjacent section to thereby cause energy of this code frequency to be cascaded to the existing entrance end of the stretch, means at each end of the stretch operative on the supply thereto of traflic reversing energy over the rails of the stretch to supply master code energy of a traffic governing code frequency to the track rails at that end of the stretch, means for each section operative on the supply thereto of traffic governing ener y at the new exit end thereof to cut off. the supply of traffic reversing energy to the section rails and to cause traffic governing energy to be supplied to the rails of the adjacent section to thereby cause the supply of traflicreversing energy to be progressively cut off and to cause the supply of trafiic'governing energy to be cascadedto the new entrance end of the stretch, and means at each end of the stretch responsive to the supply of trafiic governing energy over the rails of the stretch for controlling entrance of traflic into the stretch.

11. In combination with a stretch of track over which tramc may move in either direction, said stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, one for each direction of traffic, each set comprising a coding relay located at the corresponding exit end of the section for supplying coded energy to the section rails and a code following .track relay located at the corresponding entrance end of the section responsive to coded energy supplied over the section rails, means for each section effective when the direction of traflic in the stretch has been established to supply to the coding relay at the corresponding exit, end of the section coded energy of a trafiic governing code frequency, trafiic reversing means at each end of the stretch for changing that end of the stretch from an exit to an entrance end and comprising means to discontinue the supply of master code energy of a traffic governing frequency to the coding relay at that end of the stretch and for supplying thereto traffic reversing energy comprising master code energy of a distinctive code frequency, means for each track relay except the track relays at the ends of the stretch effective on operation of the track relay by energy of traflic reversing frequency to dis continue the supply of coded energy of traffic governing frequency to the coding relay at the adjacent end of the adjacent track section and to establish for such coding relay a circuit including a contact of the track relay to thereby cause energy of traffic reversing frequency to he cascaded throughout the stretch, means at each end of the stretch operative on the supply thereto of traffic reversing energy over the rails of the stretch to supplycoded energy of traflic governing frequency to the coding relay at the adjacent end of the track section at that end of the track stretch, each track relay except the track relays at the ends of the stretch having associated therewith means effective on operation of the relay by energy of traffic governing frequency to interrupt the circuit for supplying coded energy of traffic reversing frequency to the coding relay at that end of the track section and to cause coded energy of traffic governing frequency tobe supplied to the coding relay at the adjacent end of the adjacent section, and means at each end of the track stretch responsive to operation of the track relay at that end of the stretch by coded energy of a trafiic governing frequency to cut off the supply of coded energy of traflic reversing frequency to the coding relay at that end of the stretch and to control a signal governing entrance of traffic into the stretch.

12. In combination with a stretch of track over which trafiic may move in either direction, said track stretch being divided into a plurality of track sections, two sets of coded track circuit apparatus for each section, each set comprising a coding relay located at the correspinding exit end of the section for supplying coded energy to the section rails and a code following track relay located at the corresponding entrance end of the section responsive to coded energy supplied over the section rails, means effective when the direction of traffic in the stretch has been established to supply to the coding rela at the corresponding exit end of each section coded energy of a traflic governing code frequency, means effective when the direction of traffic in the track stretch has been established to cause the coding relay at the corresponding entrance end of the stretch to operate to supply impulses of feed-back energy to the rails of the associated track section and to cause the coding relay at the corresponding entrance end of each of the other track sections in the track stretch to operate to supply impulses of feed-back energy to the corresponding entrance end of the associated track section provided feed-back energy is being received at the adjacent end of the adjacent section, traffic reversing means at each end of the stretch for changing that end of the stretch from an exit to an entrance end and comprising means operative only when feed-back energ is being received at that end of the stretch to change the coded energy supplied to the coding relay at that end of the stretch from a traffic governing code frequency to traffic reversing energy of a distinctive code frequency, means for each track relay except the track relays at the ends of the stretch effective on operation of the track relay by energy of trafiic reversing frequency to discontinue the supply of coded energy of traffic governing frequenc to the coding relay at the adjacent end of the adjacent track section and to establish for such coding relay a circuit including a contact of the track relay to thereb cause energy of trafiic reversing frequency to be cascaded throughout the stretch, means at each end of the stretch effective on operation of the track relay at that end of the stretch by coded energy of traffic reversing code frequency to supply coded energy of traflic governing code frequency to the coding relay at the adjacent end of the track section at that end of the track stretch, each track relay except the track relays at the ends of the stretch having associated therewith means effective on operation of the relay by energy of traffic governing frequency to interrupt the circult for supplying coded energy of trafiic reversing frequency to the coding rela at that end of the track section and to cause coded energy of trailic governing frequency to be supplied to the coding relay at the adjacent end of the adjacent section, and means at each end of the track stretch responsive to operation of the track relay at that end of the stretch by coded energy of a traffic governing frequency to control a signal governing entrance of traffic into the stretch and to cut off the suppl of coded energy of traific reversing frequency to the coding rela at that end of the stretch and condition said coding relay to supply impulses of feed-back energy to the rails of the associated section,

13. In coded track circuit signaling apparatus for adjacent ends of adjacent first and second sections in a single track stretch over which traffic may move in either direction, a code following track relay for each section operated by energy supplied over the rails of the associated section, a coding relay for each section governing the supply of coded energ to the section rails, a first and a second directional stick relay, means effective when the first directional stick relay is energized to supply coded energy of a traffic governing code frequency to the coding rela for the second section, means effective when the second directional stick relay is energized to supply coded energy of a traffic governing code frequency to the coding relay for the first section, means responsive to operation of the track relay for the first section by traffic reversing energy of a distinctive code frequency to cut off the supply of coded energy of trafiic governing code frequency to the coding relay for the second section, to release the first directional stick relay and to thereafter establish a circuit including a back contact of the second directional stick relay and a contact of said track relay for supplying energy to the coding relay for said second section, means responsive to operation of the track relay for the second section by traflic reversing energy of said distinctive code frequency to cut off the supply of coded energ of trafiic governing code frequency to the coding relay for the first section, to release the second directional stick relay and to thereafter establish a circuit including a back contact of the'first directional stick relay and a contact of said track relay for supplying energy to the coding relay for said first section, means responsive to coding operation of the track relay for the second section when the track relay for the first section is operated by trafiic reversing energy to establish a pick-up circuit for said second directional stick relay, and means responsive to coding operation of the track relay for the first section when the track relay for the second section is operated by traffic reversing energy to establish a pick-up circuit for said first directional stick relay.

ARTHUR L. JEROME. 

